Method for fabricating cmos image sensor

专利摘要:
The present invention is to provide a method for manufacturing a CMOS image sensor for improving the light sensitivity by reducing the amount of light reflected before reaching the photodiode by reducing the number of layers to the maximum path to the photon incident According to an aspect of the present invention, there is provided a CMOS image sensor manufacturing method comprising: a first step of forming an optical sensing device, an interlayer insulating film, and a metal wiring; A second step of forming a protective film for protecting the device: a third step of selectively etching a portion of the interlayer insulating film stacked on the photosensitive device and the protective film; And forming a planarization layer of a single layer through which light is transmitted on the resultant of the third step. The third step is performed during a mask and etching process for opening a conventional pad.
公开号:KR20000044562A
申请号:KR1019980061061
申请日:1998-12-30
公开日:2000-07-15
发明作者:안기웅
申请人:김영환；현대전자산업 주식회사；
IPC主号:

专利说明:

Manufacturing method of CMOS image sensor with improved light sensitivity
The present invention relates to a complementary metal oxide semiconductor (CMOS) image sensor, and more particularly, to a CMOS image sensor with improved light sensitivity and a method of manufacturing the same.
CCD (charge coupled device) has a number of disadvantages such as complicated driving method, high power consumption, large number of mask process steps, complicated process, and difficult to implement signal processing circuit in CCD chip. Recently, in order to overcome such drawbacks, the development of CMOS image sensors using sub-micron CMOS manufacturing technology has been studied a lot. The CMOS image sensor forms an image by forming a photodiode and a MOS transistor in a unit pixel and sequentially detects signals in a switching method, and implements an image by using a CMOS manufacturing technology, which consumes less power and uses 30 to 40 masks as many as 20 masks. Compared to CCDs requiring two masks, the process is much simpler, and it is possible to make various signal processing circuits and one chip, which is attracting attention as the next generation image sensor. However, until now, since image quality is lower than CCD, efforts are being made to improve this. That is, in the CCD or CMOS image sensor, the photodiode is an introduction part that converts light incident to each wavelength into an electrical signal. Ideally, the incident light has a photoelectric efficiency of 1 at all wavelengths. Efforts are underway to collect all of them.
1 is a cross-sectional view schematically showing a conventional CMOS image sensor.
Referring to FIG. 1, in the conventional image sensor, an optical sensing element is formed by a photodiode 103 formed in the semiconductor substrate 101, and an interlayer insulating film 104 and a passivation layer 106 are formed thereon. ) And a color filter 107 are stacked, and a microlens 108 for collecting light to the photodiode 103 is formed on the color filter 107. Depending on the type of device or the degree of integration, the interlayer insulating film 104 is composed of at least two layers. Reference numeral 102 denotes a field insulating film, and 105 denotes a metal wiring.
As described above, the conventional image sensor has a structure in which a plurality of layers exist in a path where photons are incident to the photodiode 103. Since the reflection of light mainly occurs at the boundary of each layer, It is necessary to reduce the number of thin films formed on the substrate as much as possible.
The present invention has been made to solve the problems of the prior art as described above, by reducing the maximum number of layers in the path of the photon incident to the maximum amount of light reflected before reaching the photodiode It is an object of the present invention to provide a method for manufacturing a CMOS image sensor for improving light sensitivity.
1 is a cross-sectional view schematically showing a conventional CMOS image sensor.
2A to 2F are cross-sectional views of a manufacturing process of an image sensor according to an exemplary embodiment of the present invention.
* Explanation of symbols for the main parts of the drawings
201: semiconductor substrate 202: field insulating film
203: photodiode 204: interlayer insulating film
205: metal wiring 206: protective film
207 photoresist pattern 208 planarization layer
209: color filter 210: microlens
The CMOS image sensor manufacturing method of the present invention for achieving the above object comprises a first step of forming a photosensitive device, an interlayer insulating film and a metal wiring; A second step of forming a protective film for protecting the device: a third step of selectively etching a portion of the interlayer insulating film stacked on the photosensitive device and the protective film; And forming a planarization layer of a single layer through which light is transmitted on the resultant of the third step.
Preferably, the third step is performed during the mask and etching process for the conventional pad opening.
DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. do.
2A to 2F are cross-sectional views of a manufacturing process of an image sensor according to an exemplary embodiment of the present invention.
First, referring to FIG. 2A, in a conventional image sensor manufacturing process, a field insulating film 102 is formed on a semiconductor substrate 201, a photodiode 203 is formed, an interlayer insulating film 204 is formed, and a metal wiring 205 is formed. Is carried out. The metal layer does not remain on the photodiode 203. At least two or more layers of the interlayer insulating film 204 are laminated.
Subsequently, referring to FIG. 2B, a protective film 206 for protecting the device is formed, and as shown in FIG. 2C, an area of a pad (not shown) for wire bonding is opened during the assembly process. At the same time, the photoresist pattern 207 is formed so that the upper region of the photoresist 203 is also opened. In the prior art, only the pad region was opened when the photoresist was formed, but it should be noted that the upper region of the photodiode 203 was also opened in the present invention.
Subsequently, as shown in FIG. 2D, a portion of the passivation layer 206 and the interlayer insulating layer 204 in the upper region of the photodiode 203 as well as the pad region are removed, so that as few layers as possible remain on the photodiode 9203. do.
Next, as shown in FIG. 2E, after the photoresist pattern 207 is removed, a single layer planarization layer 208 through which light is transmitted, such as photoresist or spin on glass (SOG), is applied to the entire surface of the wafer. Again the planarization layer 208 of the pad region (not shown) is removed.
2F, in the case of an image sensor for implementing a color image, a color filter 209 having selectivity only for a specific color is formed, and then a microlens is formed thereon if necessary.
In an embodiment of the present invention, a method of directly forming the color filter 209 instead of the planarization layer 208 may be applicable, and the planarization material used may be etched back or chemical mechanical polishing (if necessary). It is also possible to use a CMP) process to reduce the thickness.
As such, although the technical idea of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.
The present invention minimizes the number of layers formed on the photodiode to minimize the reflection of photons in the process of incidence to the photodiode. As a result, the number of photocharges generated in the photodiode can be increased to make the image quality more clear.

权利要求:
Claims (4)
[1" claim-type="Currently amended] In the CMOS image sensor manufacturing method,
Forming a photosensitive device, an interlayer insulating film, and a metal wiring;
Second step of forming a protective film for protecting the device:
Selectively etching a portion of the interlayer insulating layer stacked on the photosensitive device and the passivation layer; And
A fourth step of forming a planarization layer having a single layer through which light is transmitted on the resultant of the third step;
CMOS image sensor manufacturing method comprising a.
[2" claim-type="Currently amended] The method of claim 1,
And forming a color filter on the planarization layer and forming a microlens on the color filter.
[3" claim-type="Currently amended] The method according to claim 1 or 2,
The third step is a CMOS image sensor manufacturing method, characterized in that performed during the mask and etching process for the conventional pad opening.
[4" claim-type="Currently amended] The method of claim 3,
The planarization layer is a CMOS image sensor manufacturing method characterized in that the photoresist or SOG.

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同族专利:

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公开号 | 公开日

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引用文献:

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公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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法律状态:
1998-12-30|Application filed by 김영환, 현대전자산업 주식회사

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1998-12-30|Priority to KR1019980061061A

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2000-07-15|Publication of KR20000044562A

优先权:

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申请号 | 申请日 | 专利标题

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KR1019980061061A|KR20000044562A|1998-12-30|1998-12-30|Method for fabricating cmos image sensor|